231 
 WTNT42 KNHC 021454
 TCDAT2
  
 HURRICANE KATIA DISCUSSION NUMBER  18
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122011
 1100 AM AST FRI SEP 02 2011
  
 THE CONVECTIVE DEPICTION OF KATIA HAS IMPROVED THIS MORNING AS BOTH
 MICROWAVE IMAGERY FROM SSMIS AND CONVENTIONAL VISIBLE SATELLITE
 IMAGERY INDICATE THAT AN EYE MAY BE FORMING.  BECAUSE OF THE
 IMPROVED STRUCTURE...BOTH TAFB AND SAB DVORAK CLASSIFICATIONS CAME
 IN AT A 4.0...OR 65 KT...AS DID A 1053Z CIMSS AMSU INTENSITY
 ESTIMATE.  THUS KATIA HAS REGAINED HURRICANE STATUS.
 
 THE HURRICANE IS MOVING TOWARD THE WEST-NORTHWEST AT ABOUT 12
 KT...AS IT IS BEING ADVECTED AROUND THE SOUTHWEST PERIPHERY OF A
 DEEP-LAYER RIDGE.  KATIA SHOULD MOVE TOWARD THE WEST-NORTHWEST OR
 NORTHWEST FOR THE NEXT FEW DAYS AT A SLIGHTLY SLOWER RATE OF SPEED.  
 ALL OF THE RELIABLE GUIDANCE...WITH THE EXCEPTION OF THE UKMET WHICH
 HAS A MUCH MORE EQUATORWARD SOLUTION DUE TO A SHORT-WAVE TROUGH OFF
 OF THE U.S. EAST COAST LIFTING OUT TO THE NORTHEAST MORE QUICKLY...
 IS IN EXCELLENT AGREEMENT.  THE TRACK FORECAST IS VERY SIMILAR TO
 THE PREVIOUS ADVISORY AND THE CONSENSUS OF THE GLOBAL AND HURRICANE
 MODELS LESS THE UKMET MODEL.
 
 DESPITE BECOMING A HURRICANE AGAIN...KATIA FACES A RELATIVELY
 HOSTILE ENVIRONMENT WITH SOUTHWEST VERTICAL SHEAR OF 15-20 KT
 SUGGESTED FOR THE NEXT DAY OR TWO.  BEYOND 48 HOURS...THE SHEAR
 FROM THE GLOBAL MODELS IS ANTICIPATED TO DECREASE...BUT THE
 THERMODYNAMICS MAY NOT BE IDEAL WITH LOW HUMIDITIES AND A MORE
 STABLE ENVIRONMENT ANTICIPATED.  SOME OF THE UPPER-LEVEL
 TEMPERATURE INCREASES ANALYZED IN THE SHIPS/LGEM STATISTICAL
 MODELS...HOWEVER...MAY BE SPURIOUS...AS THE STRONGER VORTEX FROM
 THE GFS MAY BE THE CAUSE OF THESE VALUES RATHER THAN THE
 ENVIRONMENT.  THUS THE SHIPS/LGEM GUIDANCE MAY BE TOO LOW AT DAYS
 THREE TO FIVE. THE INTENSITY PREDICTION IS SLIGHTLY LOWER THAN A
 SHIPS/LGEM/HWRF BLEND BUT HIGHER THAN THE PREVIOUS ADVISORY DURING
 THE NEXT TWO DAYS.
 
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  02/1500Z 17.5N  52.4W   65 KT  75 MPH
  12H  03/0000Z 18.6N  53.8W   65 KT  75 MPH
  24H  03/1200Z 19.6N  55.2W   70 KT  80 MPH
  36H  04/0000Z 20.6N  56.4W   75 KT  85 MPH
  48H  04/1200Z 21.7N  57.9W   80 KT  90 MPH
  72H  05/1200Z 24.0N  61.0W   90 KT 105 MPH
  96H  06/1200Z 26.0N  64.0W   95 KT 110 MPH
 120H  07/1200Z 27.0N  67.0W  100 KT 115 MPH
  
 $$
 FORECASTER LANDSEA/STEWART